Protective joist cover

ABSTRACT

A protective joist cover is adapted to cover a joist. The joist cover includes a top section and a bottom section. The top section has a top end web and a pair of substantially parallel top side webs each extending from an end of the top end web. The top side webs are substantially perpendicular to the top end web. The bottom section has a bottom end web and a pair of substantially parallel bottom sides webs each extending from an end of the bottom end web. The bottom side webs are substantially perpendicular to the bottom end web. The pair of top side webs and the pair of bottom side webs are dimensioned such that they overlap when positioned over the joist. The protective joist cover is made of a thermoplastic material.

FIELD OF THE INVENTION

[0001] This invention relates to decks and other outside constructions, and in particular to a protective joist cover which is meant to prevent moisture damage to joists and to prevent leaching of chemical preservatives when treated lumber joists are used in building a deck or other outside constructions.

BACKGROUND OF THE INVENTION

[0002] The majority of decks constructed in North America are constructed from wood, this includes the support structure as well as the decking surface. However, with age and exposure to moisture, wood can split, warp, twist, splinter and rot. These effects are most apparent on the horizontal decking surfaces where water can collect, especially if the deck boards become cupped. As a result, a number of manufacturers have started offering non-wood decking products which can be used as an alternative to wood decking. These products, are said to offer a number of advantages over wood, particularly relating to the moisture resistance of the materials used in their manufacture. Non-wood decking products are currently produced from a wide range of materials including thermosetting and thermoplastic resins with and without fillers. There are non-wood decking products produced with glass fiber reinforced thermosetting resins via pultrusion. However, these products are generally substantially more expensive than those products made from thermoplastic resins, which are typically produced via extrusion from virgin and recycled resins with and without fillers. Most, if not all, of the non-wood decking products produced with thermoplastic resins are made from either polyethylene (PE), polypropylene (PP), polystyrene (PS) or polyvinyl chloride (PVC), which are available quite readily in virgin or less readily in recycled forms. Non-wood decking products are available that are made with unfilled PE, PS and PVC as well as filled PE, PP and PVC. The most common type of fillers used in producing thermoplastic non-wood decking products are glass fibers and cellulosic fibers. Glass fibers are used to increase the strength of the non-wood decking products, while cellulosic fibers can be used to both increase the strength of the products and to reduce their cost, as the cellulosic fibers typically used are substantially cheaper than the resins to which they are added.

[0003] While there are a growing number of manufacturers of these non-wood decking products, most of these manufacturers recommend against using their products as framing members or joists, as they are not designed for that purpose or they do not have the strength and stiffness required by the application. Typically, the manufacturers of the non-wood decking products recommend using wood to construct the structure on which the non-wood decking product is installed. This results in a decking surface which may have a lifetime guarantee, while the wooden structure supporting it is still prone to moisture damage and may need replacement if the damage is severe enough. The effects of moisture on the wooden support structure can be minimized by using naturally moisture resistant wood species such as cedar or redwood, which are usually sold at a substantial premium to less moisture resistant species. However, while using moisture resistant wood species delays the decay of the wood, it does not prevent splitting, warping, twisting and splintering of the wood which is caused by repeated cycles of the wood getting wet and drying out.

[0004] A more economical solution than using moisture resistant wood species as joists when building decks with the non-wood decking products, has been to use lumber treated with various preservative formulations. The various chemical formulations used in treating lumber typically act as fungicides which enhance the moisture resistance of the wood by killing fungi which can lead to rot and decay. However, according to the Canadian Environment Ministry, all chemical wood preservatives are classified as pesticides as they achieve decay control as a result of their significant toxicity, and that while the potency of the various preservatives varies, all are poisonous to some degree and are potentially hazardous to human and other forms of life. In addition, the effect of the pressure treating can decrease over time as the preservatives leach out of the wood. As the preservatives leach out of the wood, it increases the potential for someone coming into contact with increased concentrations of these toxic chemicals. In addition the leached preservatives may also contaminate the soil near the structures built with treated lumber.

[0005] As a result of concerns regarding the toxicity of the arsenic and chromium compounds which result from the breakdown of the wood preservative chromated copper arsenate (CCA), the United States Environmental Protection Agency announced the phase-out of CCA treated lumber by the treated lumber industry by Dec. 31, 2003. At the time of the announcement in February of 2002, CCA treated lumber accounted for over 80% of pressure treated lumber sold in North America. Other chemical preservatives are currently available, with the most likely successor to CCA being alkaline copper quaternary (ACQ), which is substantially more expensive than CCA and is expected to result in higher treated lumber prices. However, as mentioned before, all of these preservatives prevent wood decay as a result of their toxicity and could be potentially hazardous to people.

[0006] One means available to reduce the amount of the preservatives that leach out of treated lumber, is to coat the treated lumber with paint, stain or other sealing agent. This is also a recommended means for reducing the effects of moisture damage to both moisture resistant and other wood species. However, these coatings need to be maintained and have to be reapplied periodically and the preservatives in treated lumber can interfere with the adhesion of the coatings to the surface of the wood. In addition, as the joists of most decks are not as readily accessible as the deck surfaces, it may be quite difficult to maintain the joists once the decking surface has been installed. As a result, it may be possible to have a relatively maintenance free decking surface with the non-wood decking products, while having to paint or treat the joists every year.

[0007] Several earlier patents have tried to address some of the above concerns. U.S. Pat. No. 4,516,756 and U.S. Pat. No. 6,260,328 describe sleeves made of moisture resistant thermoplastic resins into which pieces of lumber can be inserted. The purpose of the sleeves is to prevent moisture from reaching the wood. As the dimensions of stock lumber can vary by as much as ⅛ of an inch in both height and width, having a fixed size sleeve could result in the sleeve not fitting pieces of lumber of above average dimensions or being unacceptably loose on pieces of below average dimensions. U.S. Pat. No. 4,181,764 and U.S. Pat. No. 6,231,994 both deal with the problem of the varying dimensions of lumber by extruding a thermoplastic coating directly onto the lumber, while U.S. Pat. No. 6,231,994 is also directed at preventing leaching of preservative meant to prevent the decay of the lumber. However, both approaches, coating lumber with thermoplastics and using thermoplastic sleeves, are not suitable for use with an existing deck, in the case, for instance, when a wood decking surface is to be replaced with a non-wood decking product and it is desired to retrofit the existing joists with a protective thermoplastic covering.

[0008] Therefore it would be desirable to provide a product which can be used to reduce the leaching of and exposure to the preservatives used in treated lumber joists and would eliminate the need for periodic maintenance required by paints or coatings which are currently used to reduce the detrimental effects of moisture on wood. It would also be desirable if such a product could be used both in new construction and in retrofitting existing structures. In addition, it would be desirable to have a product that can compensate for the varying dimensions of standard sized lumber. Finally, it would be advantageous if the product were made of a moisture resistant material.

SUMMARY OF THE INVENTION

[0009] A protective joist cover is adapted to cover a joist. The joist cover includes a top section and a bottom section. The top section has a top end web and a pair of substantially parallel top side webs each extending from an end of the top end web. The top side webs are substantially perpendicular to the top end web. The bottom section has a bottom end web and a pair of substantially parallel bottom sides webs each extending from an end of the bottom end web. The bottom side webs are substantially perpendicular to the bottom end web. The pair of top side webs and the pair of bottom side webs are dimensioned such that they overlap when positioned over the joist. The protective joist cover is made of a thermoplastic material.

[0010] The present invention comprises a protective joist cover which consists of a top section and a bottom section which are preferably made from a moisture resistant thermoplastic material. The top section consists of a top end web which sits against the top of a joist when installed and two top side webs which are substantially parallel and extend downwardly from and perpendicular to the top end web. Similarly, the bottom section of the protective joist cover consists of a bottom end web which sits against the bottom of a joist when installed and two bottom side webs which are substantially parallel and extend upwardly from and perpendicular to the bottom end web. When installed, the ends of the top side webs overlap the ends of the bottom side webs, thereby effectively enclosing the joist. The top and bottom sections may overlap such that the bottom side webs fit between the top side webs and the sides of the joist. Alternatively the top and bottom sections may overlap such that one bottom side web fits between a top side web and one side of the joist and the other bottom side web fits outside of the other top side web which fits next to the other side of the joist.

[0011] In a preferred embodiment of the invention, the two sections of the protective joist cover are produced by selectively cutting a single hollow profile into two pieces. In addition, the joist cover can be preferably dimensioned so that it readily fits standard lumber joist sizes, while allowing for some adjustability to compensate for joists which are above average or below average in size. The protective joist cover of this invention might be designed as to specifically fit one size of joist (such as only 2×8's) or to fit two successive sizes of joists (such as 2×6's and 2×8's or 2×8's and 2×10's). An alternate embodiment of the present invention has a bottom section whose side webs are designed so that the outside dimensions at the beginning of side webs is the same as the outside dimension of the top side webs, while the outside dimension at the ends of the bottom side webs is the same as the inside dimension of the top side webs. Additionally, the joist cover can be formed with surface features on the inside surfaces of the top and bottom sections which are designed to space the joist cover away from the joist for the purpose of properly positioning the joist cover or for allowing for the circulation of air along the surfaces of the joist.

[0012] Preferably the protective joist cover is made from a moisture resistant material such as a thermoplastic resin which may or may not contain fillers whose purpose is to either increase the strength and stiffness of the profile or to reduce its cost. Further, the choice of the moisture resistant material should yield a product with sufficient strength and rigidity that minimum effort is required for installation of the product.

[0013] Other features and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments and illustrate various features and designs thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0015]FIG. 1 is a cross-sectional view of an embodiment of a protective joist cover constructed in accordance with the present invention;

[0016]FIG. 2 is a perspective view of the embodiment of the protective joist cover shown in FIG. 1;

[0017]FIG. 3 is a cross-sectional view of a hollow profile which can be selectively cut to produce the embodiment of the protective joist cover of the present invention shown in FIG. 1;

[0018]FIG. 4 is a perspective view of a hollow profile which can be selectively cut to produce the embodiment of the protective joist cover of the present invention shown in FIG. 1;

[0019]FIG. 5a is a cross-sectional view of the installation of the embodiment of the protective joist cover shown in FIG. 1 on a wood 2×8;

[0020]FIG. 5b is a cross-sectional view of the installation of the embodiment of the protective joist cover shown in FIG. 1 on a wood 2×6;

[0021]FIG. 6a is a cross-sectional view of an alternate embodiment of a hollow profile which can be selectively cut to produce an alternate embodiment of the protective joist cover of the present invention;

[0022]FIG. 6b is a cross-sectional view of an alternate embodiment of the protective joist cover shown installed over a wood 2×8 joist;

[0023]FIG. 6c is a cross-sectional view of an alternate embodiment of the protective joist cover shown installed over a wood 2×6 joist;

[0024]FIG. 7a is a cross-sectional view of a second alternate embodiment of a hollow profile which can be selectively cut to produce a second alternate embodiment of the protective joist cover of the present invention;

[0025]FIG. 7b is a cross-sectional view of a second alternate embodiment of the protective joist cover shown installed over a wood 2×8 joist;

[0026]FIG. 7c is a cross-sectional view of a second alternate embodiment of the protective joist cover shown installed over a wood 2×6 joist;

[0027]FIG. 8a is a cross-sectional view of a third alternate embodiment of a hollow profile which can be selectively cut to produce a third alternate embodiment of the protective joist cover of the present invention;

[0028]FIG. 8b is a cross-sectional view of a third alternate embodiment of the protective joist cover shown installed over a wood 2×8 joist;

[0029]FIG. 8c is a cross-sectional view of a third alternate embodiment of the protective joist cover shown installed over a wood 2×6 joist;

[0030]FIG. 9a is a cross-sectional view of a fourth alternate embodiment of a hollow profile which can be selectively cut to produce a fourth alternate embodiment of the protective joist cover of the present invention;

[0031]FIG. 9b is a cross-sectional view of a fourth alternate embodiment of the protective joist cover of the present invention;

[0032]FIG. 9c is a cross-sectional view of the fourth alternate embodiment of the protective joist cover shown in FIG. 9b, shown installed over a wood 2×8 joist;

[0033]FIG. 10a is a cross-sectional view of a fifth alternate embodiment of a hollow profile which can be selectively cut to produce a fifth alternate embodiment of the protective joist cover of the present invention;

[0034]FIG. 10b is a cross-sectional view of a fifth alternate embodiment of the protective joist cover of the present invention;

[0035]FIG. 10c is a cross-sectional view of the fifth alternate embodiment of the protective joist cover shown in FIG. 10b, shown installed over a wood 2×8 joist;

[0036]FIG. 11a is a cross-sectional view of a sixth alternate embodiment of a hollow profile which can be selectively cut to produce a sixth alternate embodiment of the protective joist cover of the present invention;

[0037]FIG. 11b is a cross-sectional view of a sixth alternate embodiment of the protective joist cover of the present invention;

[0038]FIG. 11c is a cross-sectional view of the sixth alternate embodiment of the protective joist cover shown in FIG. 11b, shown installed over a wood 2×6 joist;

[0039]FIG. 12a is a cross-sectional view of a seventh alternate embodiment of a hollow profile which can be selectively cut to produce a seventh alternate embodiment of the protective joist cover of the present invention:

[0040]FIG. 12b is a cross-sectional view of a seventh alternate embodiment of the protective joist cover of the present invention; and

[0041]FIG. 12c is a cross-sectional view of the seventh alternate embodiment of the protective joist cover shown in FIG. 12b, shown installed over a wood 2×8 joist.

DETAILED DESCRIPTION OF THE INVENTION

[0042] Although the invention will be described in terms of specific embodiments, it will be readily apparent to those skilled in the art that various modifications, rearrangements and substitutions can be made without parting from the spirit of this invention. For example, the invention herein is described as a joist cover but it will be appreciated by those skilled in the art that it could also be used to cover other building members.

[0043]FIG. 1 shows a cross-section of one embodiment of a protective joist cover of this invention, while FIG. 2 shows a perspective view of the same embodiment. The protective joist cover consists of a top section 1 and a bottom section 2. The top section 1 consists of a top end web 3 and two top side webs 4 and 5 which extend downwardly from the opposed ends 6 and 7 of the top end web 3 and are generally parallel to each other and perpendicular to the top end web 3. Similarly, the bottom section 2 consists of a bottom end web 8 and two bottom side webs 9 and 10 which extend upwardly from the ends 11 and 12 of the bottom end web 8 and are generally parallel to each other and perpendicular to the bottom end web 8. In this embodiment, the ends 13 and 14 of the top side webs 4 and 5 and the ends 15 and 16 of the bottom side webs 9 and 10 are angled to aid in the installation of the protective joist cover.

[0044] As it can be substantially easier to extrude one hollow profile than two separate open profiles, and to do so at higher production rates, it is preferred to form the two sections of the protective joist cover by selectively cutting into two pieces a single generally rectangular hollow profile which has been extruded from a moisture resistant thermoplastic material which may or may not contain a filler. As is shown in FIG. 3, if the hollow extruded profile 17, shown in a perspective view in FIG. 4, is selectively cut as indicated by lines 18 and 19, then the two sections 1 and 2 of the protective joist cover shown in FIG. 1 are formed. The hollow extruded profile 17 can have inside corners 20 and outside corners 21 with radii that have been chosen to ensure the strength of the corners during installation and to provide stress relief for the corners in case there are any forces which are concentrated at the corners when the resulting joist cover is installed.

[0045]FIG. 5a illustrates the installation of the protective joist cover shown in FIG. 1 on a nominal wood 2×8 22 (actually about 1.5 inches wide and about 7.5 inches tall). As can be seen, when the protective joist cover is installed, the end portions 23 and 24 of the bottom side webs 9 and 10 are positioned between the end portions 25 and 26 of the top side webs 4 and 5. When the protective joist cover is installed on a joist, the top side web end portions 25 and 26 and the bottom side web sections 23 and 24 should overlap each other and effectively enclose the joist. The length of the top side webs 4 and 5 and the bottom side webs 9 and 10 should be such that the length of the overlaps 29 and 30 are long enough to prevent water from wicking up between the top side webs 4 and 5 and the bottom side webs 9 and 10 while allowing for some adjustability due to the variation in the height of different 2×8's. In order to fasten the protective joist cover to the joist 22, it is only necessary to place fasteners along the length of the joist in the regions 29 and 30 where the top side webs 4 and 5 and the bottom side webs 9 and 10 overlap. Fasteners such as screws, nails, brads, staples, etc. may be appropriate depending on the thermoplastic material from which the protective joist cover has been made.

[0046]FIG. 5b illustrates the installation of the protective joist cover shown in FIG. 1 on a nominal wood 2×6 31 (actually about 4.5 inches wide and about 5.5 Inches tall). As can be seen, the protective joist cover fits the 2×6 31 in addition to fitting the 2×8 22. However, depending on the material used to produce the joist cover, the resulting bending in the beginning portions 32 and 33 of the bottom side webs 4 and 5 could be unacceptable as the stresses in the material might cause the bottom section 2 of the joist cover to break or crack, particularly at the corners 34 and 35 where the stresses would be concentrated.

[0047]FIG. 6a shows an alternative embodiment of a hollow profile 36, which when cut along lines 37 and 38 forms the alternative embodiment of the protective joist cover of this invention which is shown in FIG. 6b. When this embodiment of the protective joist cover of this invention is installed on a joist, one bottom side web end portion 39 is positioned between one top side web end portion 40 and one side of the joist 41, while the other top side web end portion 42 is positioned between the other bottom side web end portion 43 and the other side of the joist 44. As can be seen in FIG. 6c, this embodiment does not result in the bending of the bottom side webs 45 and 46 when the joist cover is installed on a 2×6. However, as a result of the side web end portion 43 being positioned outside of top side web end portion 42, there is an increased possibility for water to penetrate inside of the joist cover. If the joist cover is made from polyvinyl chloride (PVC or vinyl) or acrylonitrile-butadiene-styrene (ABS) resins, then the adhesives which are used to join PVC and ABS pipe and fittings might be used to form a watertight connection between the top section 47 and the bottom section 48 of this embodiment of the protective joist cover, if these adhesives are applied to the adjoining surfaces 49 and 50.

[0048]FIG. 7a shows a second alternative embodiment of a hollow profile 51, which when cut along lines 52 and 53 forms the alternative embodiment of the protective joist cover of this invention which is shown in FIG. 7b, installed on a 2×8. In this embodiment, the hollow profile 51 has been extruded with additional inside surface features. The surface features or detents 54 extend inwardly on the inside surface of the top end web 55 and the surface features 56 on the inside surface of the bottom end web 57 serve to space the joist cover away from the top end of the joist 58 and the bottom end of the joist 59. This allows for air to circulate between the joist cover and the joist and to keep any moisture which might collect on the inside surface of the bottom end web 57 from contacting the joist until it evaporates or drains out. The surface features or detents 60 and 61 extend inwardly on the inside surfaces 62 of the top side webs 63 and the inside surfaces 64 of the bottom side webs 65 are meant to properly center the joist cover on the 2×8 joist 66. In this case the surface features 60 and 61 are shaped to allow for easier installation of the joist cover on the joist 66. FIG. 7c shows that when the same protective joist cover shown in FIG. 7b is installed on a 2×6 joist 67, again there is bending of the bottom side webs 65, as was seen in FIG. 5b, which might result in unacceptable stresses in the joist cover when it is installed.

[0049]FIG. 8a shows a third alternative embodiment of a hollow profile 69, which when cut along lines 70 and 71 forms the alternative embodiment of the protective joist cover of this invention which is shown in FIG. 8b installed on 2×8 68. As was seen, in FIG. 6b and FIG. 6c, this offset arrangement of the top side webs 72 and 72 a and the bottom side webs 73 and 73 a gives a protective joist cover whose sides do not get bent when the joist cover is installed on a 2×6 74, as is shown in FIG. 8c. Again, surface features or detents 75 can be provided on the inside surfaces 76 of the top side webs and the inside surfaces 77 of the bottom side webs to help properly position the protective joist cover on a joist. In this case with the offset arrangement of the top side webs 72 and 72 a and the bottom side webs 73 and 73 a, the surface features 75 would only be included the top side web 72 and bottom side web 73 which are spaced away from the sides 78 and 79 of the joist 68. Even though no surface features are shown on the top web inside surface 80 and bottom end web inside surface 81 for this particular embodiment with the offset arrangement of the top side webs 72 and 72 a and bottom side webs 73 and 73 a, that does not preclude them from being included in other embodiments of the protective joist cover of this invention. However, as was noted before in regard to FIGS. 6a, 6 b and 6 c, while this offset arrangement of the side webs allows for easier use of the protective joist cover on 2×6's or 2×8's, there is the worry of water penetrating the joist cover between the adjoining surfaces 82 of top side web 72 a and bottom side web 73.

[0050]FIG. 9a shows a fourth alternative embodiment of a hollow profile 83, which when cut along lines 84 and 85 forms the alternative embodiment of the protective joist cover of this invention which is shown in FIG. 9b. In this embodiment, the top end web 86 and the bottom end web 87 are not the same length in that the bottom end web 87 is shorter than the top end web 86 by the thickness of the side webs 88 and 89 of the hollow profile 83. As a result, the side webs of the hollow profile 88 and 89 are not completely parallel when the profile is extruded. However after hollow profile 83 is cut to produce the top section 90 and bottom section 91 of this embodiment of the protective joist cover of this invention, and the joist cover is installed on a 2×8 92, the slope of the profile's side webs 88 and 89 is no longer evident, as can be seen in FIG. 9c. It will be appreciated by those skilled in the art that if this embodiment of the joist cover were installed on a 2×6, the bottom side webs 93 would not exhibit any bending as was seen in FIGS. 5b and 7 c. With this particular configuration of the protective joist cover of this invention, surface features or detents 94 can be included on the inside surface 95 of the top end web 86 and the inside surface 96 of the bottom end web 87. However, it would only be practical to provide surface features 97 on the inside surfaces 98 of the top side webs 99. For the particular embodiment of the protective joist cover shown in FIGS. 9b and 9 c, the bottom side webs 93 would not exhibit bending as was seen in FIGS. 5b and 7 c when the protective joist cover was installed on a 2×6, and it could therefore be easily used on both 2×6's and 2×8's without the concern of moisture penetration as was seen in the embodiments of the joist cover shown in FIGS. 6b and 8 b. However, when this particular embodiment of the joist cover is installed on a 2×8, there are two gaps 100 between the inside surfaces 98 of the top side webs 99 and the sides of the joist 101 where the top side webs are not substantially supported. In addition the outside surfaces 102 of the top side webs 99 are not in line with the outside surfaces 103 of the bottom side webs 93. Both of these issues might be of concern when trying to fasten such things as railing posts to a covered joist or trying to fasten two covered joints together to form a beam.

[0051]FIG. 10a shows a fifth alternative embodiment of a hollow profile 104, which when cut along lines 105 and 106 forms the alternative embodiment of the protective joist cover of this invention which is shown in FIG. 10b. This embodiment of the protective joist cover of this invention addresses the issues raised with the previously described embodiment. When installed on a 2×8 107, the outside surfaces 108 of the top side webs 109 are in line with outside surfaces 110 of the beginning portions 111 of the bottom side webs, while the bottom side web end portions 112 are positioned between the top side web end portions 113 and the sides 114 of joist 107. In this particular embodiment of the joist cover of this invention, surface features are provided at multiple locations along the inside surfaces of the top side webs 109 which are meant to better support the top side webs 109 when forces are exerted on the outside surfaces 108 of the top side webs 109. Similarly, surface features 116 are provided at multiple locations along the inside surfaces of bottom side webs 111, again to better support them. This embodiment shows an alternate surface treatment 124 applied to top end web 125 and bottom end web 126. Surface treatment 124 is a plurality of groves formed in the inside surface of the web.

[0052] While the last embodiment of the protective joist cover of this invention addresses the issues raised with the previously described embodiment, it can only effectively be used with 2×8 joists as it is not possible to overlap the top and bottom side webs so that the top and bottom end webs rest against the top and bottom of a 2×6. As such, FIG. 11a shows a sixth alternative embodiment of a hollow profile 117, which when cut along lines 118 and 119 form the alternative embodiment of the protective joist cover of this invention, shown in FIG. 11b, which has the same characteristics of the embodiment of the protective joist cover shown in FIG. 10b, but is dimensioned specifically for use with 2×6 joists, as is shown in FIG. 11c. Protective joist covers for 2×10's and 2×12's incorporating the same features can also be easily designed.

[0053]FIG. 12a shows the hollow profile shown in FIG. 3, but in order to produce a seventh alternate embodiment of the protective joist cover of this invention, the hollow profile is cut along lines 120 and 121 and form the joist cover which is shown in FIGS. 12b and 12 c. As can be seen, in this embodiment of the protective joist cover, the top side webs 127 and the bottom side webs 128 are substantially different in length. While this may preclude using the same joist cover on 2×6's and 2×8's, it may offer other advantages such as reducing the stresses in corners 122 and 123 when the cover is installed.

[0054] It will be appreciated by those skilled in the art that the protective joist cover of this invention might be dimensioned as to specifically fit one size of joist (such as only 2×8's) or to fit two successive sizes of joists (such as 2×6's and 2×8's or 2×8's and 2×10's). Typically a minimum overlap of 0.5 inches is preferred. However where the joist covers are dimensioned to fit two successive sizes of joists the overlap may range between 0.5 inches and 3 inches. Typically the length of the two top side webs will be between 0.5 inches and 5.5 inches for 2×6's; 0.5 Inches and 7.5 inches for 2×8's; 0.5 inches and 9.5 inches for 2×10's; and 0.5 inches and 11.5 inches for 2×12's. Similarly the length of the two bottom side webs will be between 5.5 inches and 0.5 inches for 2×6's; 7.5 inches and 0.5 inches for 2×8's; 9.5 inches and 0.5 inches for 2×10's; and 11.5 inches and 0.5 inches for 2×12's. It will be appreciated by someone skilled in the art that the relative lengths of the top side webs and bottom side webs may be chosen to accommodate in situ considerations.

[0055] As discussed above the protective joist cover of the present invention is made from thermoplastic material. The thermoplastic may be virgin resin, recycled resin or a mixture of the two. In addition, the thermoplastic material may contain filler or a combination of different fillers. A wide variety of fillers may be used and the filler chosen would depend on the properties desired, the availability of the different fillers and economic considerations. For example the filler may be glass fibers, carbon fibers, metallic fibers, thermoplastic fibers or a combination thereof. Alternatively the filler may be cellulosic fibers or particles derived by the comminution or attrition by grinding or milling of wood, plant matter or agricultural byproducts such as hulls, husks, shells and straws, or mixtures thereof. As a further alternative the filler may include cellulosic fibers from recycling or a byproduct of paper production. As a still further alternative the filler may be a mineral filler such as talc, mica, calcium carbonate or clays.

[0056] As used herein, the terms “comprises” and “comprising” are to be construed as being inclusive and opened rather than exclusive. Specifically, when used in this specification including the claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or components are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

[0057] It is to be understood that while certain embodiments of this invention have been described above, the invention is not to be limited to the specific embodiments shown and described. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification. 

What is claimed as the invention is:
 1. A protective joist cover adapted to cover a joist having a width, the protective joist cover comprising; a top section having a top end web and a pair of substantially parallel top side webs each extending from an end of the top end web and being substantially perpendicular to the top end web; a bottom section having a bottom end web and a pair of substantially parallel bottom sides webs each extending from an end of the bottom end web and being substantially perpendicular to the bottom end web and whereby the pair of top side webs and the pair of bottom side webs are dimensioned such that they overlap when positioned over the joist; and the protective joist cover being of a thermoplastic material.
 2. A protective joist cover as claimed in claim 1 wherein the distance between the inside surfaces of the pair of top side webs generally equals the width of the joist plus the thickness of the pair of bottom side webs.
 3. A protective joist cover as claimed in claim 2 wherein the distance between the inside surfaces of the pair of bottom side webs generally equals to distance between the inside surfaces of the pair of top side webs.
 4. A protective joist cover as claimed in claim 2 wherein the distance between the inside surface of the pair of bottom side webs generally equals the width of the joist.
 5. A protective joist cover as claimed in claim 2 wherein the overlap is greater than 0.5 inches.
 6. A protective joist cover as claimed in claim 2 wherein the overlap is between 0.5 and 2 inches.
 7. A protective joist cover as claimed in claim 1 wherein the pair of bottom side webs is substantially longer than the pair of top side webs.
 8. A protective joist cover as claimed in claim 7 wherein the length of the pair of top side webs is between 0.5 and 2 inches.
 9. A protective joist cover as claimed in claim 2 wherein the width of the joist is between 1.25 and 1.75 inches.
 10. A protective joist cover as claimed in claim 1 wherein the pair of top side webs and the pair of bottom side webs have the same web thickness and the distance between the inside surfaces of the pair of bottom side webs and the inside surface of the pair of top side webs is equal to the distance between the inside surfaces of the pair of top side webs and is equal to the width of the joist plus the web thickness.
 11. A protective joist cover as claimed in claim 10 wherein the overlap is greater than 0.5 inches.
 12. A protective joist cover as claimed in claim 1 wherein the inside surface of the top end web has a plurality of detents extending inwardly therefrom thereby providing an airspace between the top end web and the joist when positioned over the joist.
 13. A protective joist cover as claimed in claim 1 wherein the inside surface of the bottom end web has a plurality of detents extending inwardly therefrom thereby providing an airspace between the bottom end web and the joist when positioned over the joist.
 14. A protective joist cover as claimed in claim 2 wherein the inside surface of each of the pair of top side webs has a plurality of detents extending inwardly therefrom thereby providing an airspace between the top side web and the joist when positioned over the joist.
 15. A protective joist cover as claimed in claim 10 wherein the inside surface of the at least one of the pair of top side webs has a plurality of detents extending inwardly therefrom thereby providing an airspace between the top side web and the joist when positioned over the joist and the inside surface of the at least one of the pair of bottom side webs has a plurality of detents extending inwardly therefrom thereby providing an airspace between the bottom side web and the joist when positioned over the joist.
 16. A protective joist cover as claimed in claim 3 wherein the inside surface of each of the pair of bottom side webs has a plurality of detents extending inwardly therefrom thereby providing an airspace between the bottom side web and the joist when positioned over the joist and the inside surface of each of the pair of top side webs has a plurality of detents extending inwardly therefrom thereby providing an airspace between the top side web and the joist when positioned over the joist.
 17. A protective joist cover as claimed in claim 3 wherein a distal end portion of each of the pair of the bottom side webs is offset inwardly from a remainder portion of the respective bottom side web and is generally parallel thereto.
 18. A protective joist cover as claimed in claim 1 wherein the top end web, the pair of top side webs, the bottom end web and the pair of bottom side webs all have the same thickness.
 19. A protective joist cover as claimed in claim 1 wherein said thermoplastic material is chosen from the group consisting of a thermoplastic resin, a blend of thermoplastic resins and a mixture of thermoplastic resins.
 20. A protective joist cover as claimed in claim 1 wherein said thermoplastic resin is chosen from the group consisting of a virgin resin, a recycled resin, and a mixture of virgin and recycled resins.
 21. A protective joist cover as claimed in claim 1 wherein said thermoplastic material contains a filler.
 22. A protective joist cover as claimed in claim 21 wherein the filler is chosen from the group consisting of glass fibers, carbon fibers, metallic fibers, thermoplastic fibers and mixtures thereof.
 23. A protective joist cover as claimed in claim 21 wherein the filler is one of cellulosic fibers and cellulosic particles derived by one of the comminution and attrition by one of grinding and milling one of wood, plant matter and agricultural byproducts chosen from the group of hulls, husks, shells, straws and mixtures thereof.
 24. A protective joist cover as claimed in claim 21 wherein the filler is cellulosic fibers from one of recycling and a byproduct of paper production.
 25. A protective joist cover as claimed in claim 21 wherein said filler is a mineral filler chosen from the group consisting of talc, mica, calcium carbonate and clays.
 26. A protective joist cover as claimed in claim 1 where the protective joist cover is manufactured as a hollow profile and subsequently cut into the top section and the bottom section.
 27. A protective joist cover as claimed in claim 2 where the protective joist cover is manufactured as a hollow profile and subsequently cut into the top section and the bottom section.
 28. A protective joist cover as claimed in claim 3 where the protective joist cover is manufactured as a hollow profile and subsequently cut into the top section and the bottom section.
 29. A protective joist cover as claimed in claim 4 where the protective joist cover is manufactured as a hollow profile and subsequently cut into the top section and the bottom section.
 30. A protective joist cover as claimed in claim 7 where the protective joist cover is manufactured as a hollow profile and subsequently cut into the top section and the bottom section.
 31. A protective joist cover as claimed in claim 10 where the protective joist cover is manufactured as a hollow profile and subsequently cut into the top section and the bottom section.
 32. A hollow profile adapted to be selectively cut into a protective joist cover adapted to cover a joist having a width, the protective joist cover comprising; a top section having a top end web and a pair of substantially parallel top side webs each extending from an end of the top end web and being substantially perpendicular to the top end web; a bottom section integrally attached to the top section and adapted to be selectively cut therefrom, the bottom section having a bottom end web and a pair of substantially parallel bottom sides webs each extending from an end of the bottom end web and being substantially perpendicular to the bottom end web and whereby the pair of top side webs and the pair of bottom side webs are dimensioned such that they overlap when positioned over the joist; and the hollow profile being of a thermoplastic material. 